To diagnose an ITL signature mismatch, compare the ITL MD5 checksum shown on the phone under Settings > Security Configuration > Trust List with the ITL on the TFTP server, and check that the TVS certificate serial number matches the ITL record.
Checked 2026-10-01
- Vendor
- Cisco
- Product
- Unified Communications Manager
- Subsystem
- ITL
- Deployment
- on-premises
- Region
- not restricted
- Release range
- 8.0 and later
- Checked
- 2026-10-01
Sources
- Understand CUCM Security By Default and ITL Operation and Troubleshooting — Cisco Systems · tier 2 current vendor documentation · Troubleshoot section (ITL signature mismatch)
Cite this note
APA
WarmTransfer. (2026, October 1). Troubleshooting phone trust and ITL failures in Unified CM: source note cucm-itl-trust-troubleshooting-itl-mismatch-md5-check. WarmTransfer. https://warmtransfer.net/knowledge/claims/cucm-itl-trust-troubleshooting-itl-mismatch-md5-check
BibTeX
@misc{warmtransfer-claim-cucm-itl-trust-troubleshooting-itl-mismatch-md5-check,
title = {Troubleshooting phone trust and ITL failures in Unified CM: source note cucm-itl-trust-troubleshooting-itl-mismatch-md5-check},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/cucm-itl-trust-troubleshooting-itl-mismatch-md5-check},
note = {Source note cucm-itl-trust-troubleshooting-itl-mismatch-md5-check, checked 2026-10-01}
}